Electronic thermometers typically use an electric probe member with probe covers that may be reusable or disposable. Thermometers used in the health care industry for taking patients' temperatures use disposable covers to prevent infection and reduce sterilization costs. Contemporarily there are in use a number of different devices for holding the cover on the probe member. Some of these devices, such as cams, springs, sliding members, and various other complex and active parts, are expensive, tend to wear out, and are not trouble-free. Other devices are relatively less complex but do not provide the tight reliable fit of probe cover to probe member required with certain thermometer systems. Release mechanisms used to strip the probe cover from the probe member are often similarly complex and have met with indifferent success. Often the probe covers require some special configuration, taper, or retaining portions for cooperation with gripping and release devices, and may require special flexibility characteristics.
In many contemporary probe devices the probe cover, when in place, is under a significant stress due either to strain induced in the cover itself as by stretching or to forces actively applied to the cover by springs or other active mechanisms. This creates a danger that an inadvertantly released cover, if near or aimed at a patient, could cause harm and embarrassment. This danger is compounded when, as is often the case, the same general motion is applied to install the cover as to release it.